Optical imaging system and portable electronic device including the same

ABSTRACT

An optical imaging system includes a plurality of lenses disposed along an optical axis, and a reflection member disposed to be closer to an object than all of the plurality of lenses and having a reflection surface configured to change a path of light. The plurality of lenses are spaced apart from each other by preset distances along the optical axis, and the condition 0.8&lt;TTL/ft&lt;1.1 is satisfied, where TTL is a distance from an object-side surface of a lens closest to the object among the plurality of lenses to an imaging plane of an image sensor, and ft is an overall focal length of an optical system including the plurality of lenses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119(a) of Korean PatentApplication No. 10-2016-0182148 filed on Dec. 29, 2016, in the KoreanIntellectual Property Office, the entire disclosure of which isincorporated herein by reference for all purposes.

BACKGROUND 1. Field

This application relates to an optical imaging system and a portableelectronic device including the same.

2. Description of Related Art

Recently, mobile communications terminals have been provided withcameras, enabling video calling and image capturing. In addition, aslevels of functionality of cameras in such mobile communicationsterminals have gradually increased, cameras for use in mobilecommunications terminals have gradually been required to have higherlevels of resolution and performance.

However, since there is a trend for mobile communications terminals tobe miniaturized and lightened, there are limitations in implementingcamera modules having high levels of resolution and performance.

Telephoto lenses, particularly, have a relatively long focal length andoverall length, and it is thus difficult to mount the telephoto lensesin the mobile communications terminals.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In one general aspect, an optical imaging system includes a plurality oflenses disposed along an optical axis; and a reflection member disposedto be closer to an object than all of the plurality of lenses and havinga reflection surface configured to change a path of light; wherein theplurality of lenses are spaced apart from each other by preset distancesalong the optical axis; and the condition 0.8<TTL/ft<1.1 is satisfied,where TTL is a distance from an object-side surface of a lens closest tothe object among the plurality of lenses to an imaging plane of an imagesensor, and ft is an overall focal length of an optical system includingthe plurality of lenses.

The plurality of lenses may include a first lens, a second lens, a thirdlens, a fourth lens, and a fifth lens sequentially disposed in numericalorder beginning with the first lens from an object side of the opticalsystem toward an image side of the optical system; and the condition1.5<ft/ft1<3.5 may be satisfied, where ft1 is a focal length of thefirst lens.

The first lens may have a positive refractive power; and an object-sidesurface and an image-side surface of the first lens may be convex.

The second lens may have a negative refractive power; and an image-sidesurface of the second lens may be concave.

The third lens may have a positive refractive power or a negativerefractive power; an object-side surface of the third lens may beconvex; and an image-side surface of the third lens may be concave.

The fourth lens may have a positive refractive power; an object-sidesurface of the fourth lens may be concave; and an image-side surface ofthe fourth lens may be convex.

The fifth lens may have a negative refractive power; an object-sidesurface of the fifth lens may be concave; and an image-side surface ofthe fifth lens may be convex.

Object-side surfaces and image-side surfaces of the first, second,third, fourth, and fifth lenses may be aspherical.

The first, second, third, fourth, and fifth lenses may be plasticlenses.

The optical imaging system may further include a stop disposed in frontof the first lens; and an effective diameter of a lens having a maximumeffective diameter among the first, second, third, fourth, and fifthlenses may be greater than a diameter of the stop.

The plurality of lenses may include a first lens having a positiverefractive power; a second lens having a negative refractive power; athird lens having a positive refractive power; a fourth lens having apositive refractive power; and a fifth lens having a negative refractivepower; and the first, second, third, fourth, and fifth lenses may besequentially disposed in numerical order beginning with the first lensfrom an object side of the optical system toward an image side of theoptical system.

The plurality of lenses may include a first lens having a positiverefractive power; a second lens having a negative refractive power; athird lens having a negative refractive power; a fourth lens having apositive refractive power; and a fifth lens having a negative refractivepower; and the first, second, third, fourth, and fifth lenses may besequentially disposed in numerical order beginning with the first lensfrom an object side of the optical system toward an image side of theoptical system.

In another general aspect, a portable electronic device includes a firstoptical imaging system; a second optical imaging system; and a thirdoptical imaging system; wherein the first, second, and third opticalimaging systems have different fields of view; and a direction of anoptical axis of an optical imaging system having a narrowest field ofview among the first, second, and third optical imaging systems isdifferent from a direction of optical axes of remaining ones of thefirst, second, and third optical imaging systems.

The condition 1.8<FOVw/FOVt<4.5 may be satisfied, where FOVt is a fieldof view of the optical imaging system having the narrowest field of viewamong the first, second, and third optical imaging systems, and FOVw isa field of view of an optical imaging system having a widest field ofview among the first, second, and third optical imaging systems.

The condition 2.0<ft/fw<5.0 may be satisfied, where ft is an overallfocal length of the optical imaging system having the narrowest field ofview among the first, second, and third optical imaging systems, and fwis an overall focal length of an optical imaging system having a widestfield of view among the first, second, and third optical imagingsystems.

In another general aspect, an optical imaging system includes an opticalsystem including a plurality of lenses configured to be movable as afixed unit along an optical axis to focus on objects at differentdistances while maintaining a fixed positional relationship between theplurality of lenses; and a reflection member configured to reflect lightfrom an object into an object side of the optical system; wherein afield of view of the optical system changes as the optical system movesalong the optical axis; and the condition 0.8<TTL/ft<1.1 is satisfied,where TTL is a distance from an object-side surface of a lens closest tothe object among the plurality of lenses to an imaging plane of an imagesensor, and ft is an overall focal length of the optical system.

The optical system may include a first lens having a positive refractivepower; a second lens having a negative refractive power; a third lenshaving a positive refractive power or a negative refractive power; afourth lens having a positive refractive power; and a fifth lens havinga negative refractive power; and the first, second, third, fourth, andfifth lenses may be sequentially arranged in numerical order beginningwith the first lens from the object side of the optical system toward animage side of the optical system.

The condition 1.5<ft/ft1<3.5 may be satisfied, where ft is an overallfocal length of an optical system, and ft1 is a focal length of thefirst lens.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an example of a portableelectronic device.

FIG. 2 is a view illustrating an example of a first optical imagingsystem.

FIG. 3 is graphs showing curves illustrating aberration characteristicsof the first optical imaging system illustrated in FIG. 2.

FIGS. 4 and 5 are tables listing characteristics of lenses of the firstoptical imaging system illustrated in FIG. 2.

FIG. 6 is a table listing aspherical coefficients of lenses of the firstoptical imaging system illustrated in FIG. 2.

FIG. 7 is a view illustrating another example of a first optical imagingsystem.

FIG. 8 is graphs showing curves illustrating aberration characteristicsof the first optical imaging system illustrated in FIG. 7.

FIGS. 9 and 10 are tables listing characteristics of lenses of the firstoptical imaging system illustrated in FIG. 7.

FIG. 11 is a table listing aspherical coefficients of lenses of thefirst optical imaging system illustrated in FIG. 7.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

In the drawings, the thicknesses, sizes, and shapes of lenses have beenslightly exaggerated for convenience of explanation. In particular, theshapes of spherical surfaces or aspherical surfaces illustrated in thedrawings are illustrated by way of example. That is, the shapes of thespherical surfaces or the aspherical surfaces are not limited to thespecific shapes illustrated in the drawings.

FIG. 1 is a perspective view illustrating an example of a portableelectronic device.

Referring to FIG. 1, a portable electronic device 1000 includes aplurality of optical imaging systems, and each of the plurality ofoptical imaging systems includes a plurality of lenses.

In the example illustrated in FIG. 1, the portable electronic device1000 includes a first optical imaging system 300, a second opticalimaging system 400, and a third optical imaging system 500.

The first optical imaging system 300, the second optical imaging system400, and the third optical imaging system 500 have different fields ofview (FOVs).

In one example, the first optical imaging system 300 has the narrowestfield of view (first telephoto, 3×), the second optical imaging system400 (second telephoto, 2×) has a field of view wider than that of thefirst optical imaging system 300, and the third optical imaging system500 has the widest field of view (wide angle, lx).

In one example, the field of view (FOVt) of the first optical imagingsystem 300 is less than or equal to 40°, the field of view (FOVm) of thesecond optical imaging system 400 is greater than or equal to 40°, andthe field of view (FOVw) of the third optical imaging system 500 is in arange of 75° or more to 95° or less. However, these are only examples,and the fields of view of the first optical imaging system 300, thesecond optical imaging system 400, and the third optical imaging system500 may have other values as long as the first optical imaging system300 has the narrowest field of view, the third optical imaging system500 has the widest field of view, and the second optical imaging system400 has a field of view between the field of view of the first opticalimaging system 300 and the field of view of the third optical imagingsystem 500.

As described above, the three optical imaging systems are designed tohave different fields of view to capture an image of a subject atvarious distances and implement a zoom function.

In addition, a zoom magnification of 3× may be implemented, and anincrease in a thickness of the portable electronic device 100 may beprevented.

Further, since an image having a high level of resolution or a brightimage may be generated by using (for example, synthesizing) two imagesfor one subject, an image of the subject may be clearly captured even inan environment in which illumination is low.

In one example, an optical axis of the plurality of lenses in the secondoptical imaging system 400 and an optical axis of the plurality oflenses in the third optical imaging system 500 are oriented in athickness direction (a direction from a front surface of the portableelectronic device 1000 toward a rear surface thereof, or in an oppositedirection to such a direction) of the portable electronic device 1000,while an optical axis of the plurality of lenses of the first opticalimaging system 300, having the narrowest field of view, is orientedperpendicular to the thickness direction of the portable electronicdevice 1000.

That is, a direction of an optical axis of an optical imaging systemhaving the narrowest field of view among the first, second, and thirdoptical imaging systems 300, 400, and 500 is different from a directionof an optical axis of the other ones of the optical imaging systems.

In one example, the optical axis (a Z axis) of the plurality of lensesconstituting the first optical imaging system 300 is oriented in a widthdirection or a length direction of the portable electronic device 1000.

Therefore, an entire length of the first optical imaging system 300 doesnot have an influence on a thickness of the portable electronic device1000. Accordingly, the portable electronic device 100 may beminiaturized.

Since the optical axis of the first optical imaging system 300 isoriented to be perpendicular to the thickness direction of the portableelectronic device 1000, the first optical imaging system 300 changes apath of light incident in the thickness direction of the portableelectronic device 1000.

In one example, the first optical imaging system 300 includes areflection member P having a reflection surface that changes the path ofthe light. The reflection member P may be a mirror or a prism thatchanges the path of the light.

The first optical imaging system 300 and the third optical imagingsystem 500 satisfy the following Conditional Expressions:

1.8<FOVw/FOVt<4.5  [Conditional Expression 1]

2.0<ft/fw<5.0.  [Conditional Expression 2]

In the above Conditional Expressions, FOVw is a field of view of thethird optical imaging system 500, FOVt is a field of view of the firstoptical imaging system 300, ft is a focal length of the first opticalimaging system 300, and fw is a focal length of the third opticalimaging system 500.

The first optical imaging system 300 will hereinafter be described withreference to FIGS. 2 through 11.

The first optical imaging system 300 includes a plurality of lensesdisposed along an optical axis. The plurality of lenses are spaced apartfrom each other by preset distances along the optical axis.

In the examples described herein, the first optical imaging system 300includes five lenses.

In the examples described herein, first lens is a lens closest to anobject, while a fifth lens is a lens closest to an image sensor.

In addition, a first surface of a lens is a surface of the lens closestto an object side of the lens (i.e., an object-side surface), and asecond surface of the lens is a surface of the lens closest to an imageside of the lens (i.e., an image-side surface). Further, all numericalvalues of radii of curvature, thicknesses of lenses, and otherparameters are expressed in millimeters (mm), and angles are expressedin degrees.

Further, a statement that one surface of a lens is convex means that aparaxial region of that surface is convex, and a statement that onesurface of a lens is concave means that a paraxial region of thatsurface is concave. Therefore, although a surface of a lens may bedescribed as being convex, an edge portion of that surface may beconcave. Likewise, although a surface of a lens may be described asbeing concave, an edge portion of that surface may be convex.

A paraxial region of a surface is a very narrow region in the vicinityof an optical axis of the surface.

In examples described herein, the first optical imaging system includesa first lens, a second lens, a third lens, a fourth lens, and a fifthlens sequentially disposed in numerical order beginning with the firstlens from the object side.

However, the first optical imaging system in the examples describedherein is not limited to only including five lenses, but furtherincludes other components in addition to the five lenses.

For example, the first optical imaging system further includes an imagesensor that converts an image of a subject incident on the image sensorinto an electrical signal.

In addition, the first optical imaging system further includes aninfrared cut-off filter that blocks infrared light. The infrared cut-offfilter is disposed between a lens (the fifth lens) closest to the imagesensor and the image sensor. However, this is merely an example, and theinfrared cut-off filter may be disposed at other positions in the firstoptical imaging system.

In addition, the first optical imaging system further includes areflection member having a reflection surface that changes a path oflight. For example, the reflection member may be a mirror or a prism.

The reflection member is closer to the object than any of the lenses ofthe first optical imaging system. Therefore, a lens closest to theobject is a lens closest to the reflection member.

At least the first to fifth lenses of the first optical imaging systemmove along the optical axis for auto-focusing (AF). The reflectionmember and the infrared cut-off filter of the first optical imagingsystem may or may not move along the optical axis for auto-focusing(AF).

In the first optical imaging system in the examples described herein,all of the lenses are plastic lenses.

In addition, the first to fifth lenses each have at least one asphericalsurface.

That is, at least one of first and second surfaces of all of the firstto fifth lenses is aspherical. The aspherical surfaces of the first tofifth lenses are represented by the following Equation 1:

$\begin{matrix}{Z = {\frac{{cY}^{2}}{1 + \sqrt{1 - {\left( {1 + K} \right)c^{2}Y^{2}}}} + {AY}^{4} + {BY}^{6} + {CY}^{8} + {DY}^{10} + {EY}^{12} + {FY}^{14} + {\ldots \mspace{14mu}.}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, c is a curvature (an inverse of a radius of curvature) ofa lens, K is a conic constant, and Y is a distance from a certain pointon an aspherical surface of the lens to an optical axis of the lens in adirection perpendicular to the optical axis. In addition, constants A toF are aspherical coefficients. In addition, Z is a distance between thecertain point on the aspherical surface of the lens at the distance Yand a tangential plane meeting the apex of the aspherical surface of thelens. The ellipsis . . . in Equation 1 indicates that additional termsGY¹⁶, HY¹⁸, JY²⁰, and so on may be added to further refine the shape ofthe aspherical surface.

In one example, the first optical imaging system including the first tofifth lenses has positive, negative, positive, positive, negativerefractive powers sequentially in the order listed beginning from theobject side of the first imaging optical system.

In another example, the first optical imaging system including the firstto fifth lenses has positive, negative, negative, positive, negativerefractive powers sequentially in the order listed beginning from theobject side of the first imaging optical system.

The first optical imaging system in the examples described hereinsatisfies the following Conditional Expressions:

0.8<TTL/ft<1.1  [Conditional Expression 3]

1.5<ft/ft1<3.5.  [Conditional Expression 4]

In the above Conditional Expressions, TTL is a distance from anobject-side surface of the first lens of the first optical imagingsystem to an imaging plane of the image sensor, ft is an overall focallength of the first optical imaging system, and ft1 is a focal length ofthe first lens of the first optical imaging system.

Next, the first to fifth lenses constituting the optical imaging systemin the examples described herein will be described.

The first lens has a positive refractive power.

In addition, both surfaces of the first lens are convex. In detail,first and second surfaces of the first lens are convex in the paraxialregion.

At least one of the first and second surfaces of the first lens isaspherical. In one example, both surfaces of the first lens areaspherical.

The second lens has a negative refractive power.

In one example, a first surface of the second lens is flat in theparaxial region, and a second surface thereof is concave in the paraxialregion.

In another example, the second lens has a meniscus shape, of which anobject-side surface is convex. In detail, the first surface of thesecond lens is convex in the paraxial region, and the second surfacethereof is concave in the paraxial region.

At least one of the first and second surfaces of the second lens isaspherical. In one example, both surfaces of the second lens areaspherical.

The third lens has a positive refractive power or a negative refractivepower.

In addition, the third lens has a meniscus shape, of which anobject-side surface is convex. In detail, a first surface of the thirdlens is convex in the paraxial region, and a second surface thereof isconcave in the paraxial region.

At least one of the first and second surfaces of the third lens isaspherical. In one example, both surfaces of the third lens areaspherical.

The fourth lens has a positive refractive power.

In addition, the fourth lens has a meniscus shape, of which animage-side surface is convex. In detail, a first surface of the fourthlens is concave in the paraxial region, and a second surface thereof isconvex in the paraxial region.

At least one of the first and second surfaces of the fourth lens isaspherical. In one example, both surfaces of the fourth lens areaspherical.

The fifth lens has a negative refractive power.

In addition, the fifth lens has a meniscus shape, of which an image-sidesurface is convex. In detail, a first surface of the fifth lens isconcave in the paraxial region, and a second surface thereof is convexin the paraxial region.

At least one of the first and second surfaces of the fifth lens isaspherical. In one example, both surfaces of the fifth lens areaspherical.

In the first optical imaging system configured as described above, aplurality of lenses perform an aberration correction function to thusincrease an aberration improvement performance.

In addition, the first optical imaging system in the examples describedhere has a telephoto ratio (TTL/ft) between 0.8 and 1.1, to havefeatures of a telephoto lens and a field of view (FOV) of 40° or less.Therefore, a narrow FOV may be implemented.

An example of a first optical imaging system will now be described withreference to FIGS. 2 through 6.

FIG. 2 is a view illustrating an example of a first optical imagingsystem. FIG. 3 is graphs showing curves illustrating aberrationcharacteristics of the first optical imaging system illustrated in FIG.2. FIGS. 4 and 5 are tables listing characteristics of lenses of thefirst optical imaging system illustrated in FIG. 2. FIG. 6 is a tablelisting aspherical coefficients of lenses of the first optical imagingsystem illustrated in FIG. 2.

Referring to FIG. 2, the first optical imaging system includes anoptical system including a first lens 110, a second lens 120, a thirdlens 130, a fourth lens 140, a fifth lens 150, an infrared cut-offfilter 160, and an image sensor 170.

In addition, the first optical imaging system includes a reflectionmember P closer to an object than the first lens 110, and having areflection surface that changes a path of light. In the exampleillustrated in FIG. 2, the reflection member P is a mirror that changesthe path of the light.

Respective characteristics (radii of curvature, thicknesses or distances(gaps) between lenses, refractive indices, and Abbe numbers) of lensesare illustrated in FIG. 4.

Since the first optical imaging system moves along an optical axis forauto-focusing, a first position, a second position, and a third positionin the table illustrated in FIG. 5 refer to positions of the firstoptical imaging system depending on a distance from the first opticalimaging system to a subject whose image is being captured. In the tableillustrated in FIG. 5, D0 is the distance between the object and thereflection member P, D1 is the distance between the reflection member Pand the first surface of the first lens 110, and D2 is the distancebetween the second surface of the infrared cut-off filter 160 and theimage sensor 170. As can be seen from the table illustrated in FIG. 5,in this example, the first lens 110 to the fifth lens 150 and theinfrared cut-off filter 160 move along the optical axis forauto-focusing, but the reflection member P does not move along theoptical axis for auto-focusing.

For example, in the table illustrated in FIG. 5, the first position is aposition of the first optical imaging system when capturing an image ofa subject at infinity, the second position is a position of the firstoptical imaging system when capturing an image of a subject at a normaldistance, for example, about 1.5 m, and the third position is a positionof the first optical imaging system when capturing an image of a subjectat a macro distance, for example, about 0.4 m.

A ratio (FOVt1/FOVt3) of a field of view (FOVt1) in the first positionto a field of view (FOVt3) in the third position, that is, a ratio of amaximum field of view to a minimum field of view, is greater than 1 andless than 1.5.

In the example illustrated in FIGS. 2 through 6, the distance TTL fromthe object-side surface of the first lens 110 of the first opticalimaging system to the imaging plane of the image sensor 170 is 9.68 mm,an overall focal length ft of the first optical imaging system is 10.7mm, and an f-number Fno of the first optical imaging system is in arange of 2.6 to 3.1.

In the example illustrated in FIGS. 2 through 6, the first lens 110 hasa positive refractive power, and a first surface and a second surfacethereof are convex in the paraxial region.

The second lens 120 has a negative refractive power, a first surfacethereof is flat in the paraxial region, and a second surface thereof isconcave in the paraxial region.

The third lens 130 has a positive refractive power, a first surfacethereof is convex in the paraxial region, and a second surface thereofis concave in the paraxial region.

The fourth lens 140 has a positive refractive power, a first surfacethereof is concave in the paraxial region, and a second surface thereofis convex in the paraxial region.

The fifth lens 150 has a negative refractive power, a first surfacethereof is concave in the paraxial region, and a second surface thereofis convex in the paraxial region.

Surfaces of the first to fifth lenses 110 to 150 have asphericalcoefficients as illustrated in FIG. 6. In this example, all object-sidesurfaces and all image-side surfaces of the first to fifth lenses 110 to150 are aspherical.

In the example illustrated in FIG. 2, a stop is disposed in front of thefirst lens 110, and an effective diameter of at least one of the firstto fifth lenses 110 to 150 is greater than a diameter of the stop. Inthe example illustrated in FIG. 2, the first surface of the first lens110 protrudes through the stop, but the stop is nevertheless consideredto be disposed in front of the first lens 110.

In one example, an effective diameter of a lens having a maximumeffective diameter among the first to fifth lenses 110 to 150 is greaterthan the diameter of the stop.

The first optical imaging system configured as described above hasaberration characteristics illustrated in FIG. 3.

Another example of a first optical imaging system will be described withreference to FIGS. 7 through 11.

FIG. 7 is a view illustrating another example of a first optical imagingsystem. FIG. 8 is graphs showing curves illustrating aberrationcharacteristics of the first optical imaging system illustrated in FIG.7. FIGS. 9 and 10 are tables listing characteristics of lenses of thefirst optical imaging system illustrated in FIG. 7. FIG. 11 is a tablelisting aspherical coefficients of lenses of the first optical imagingsystem illustrated in FIG. 7.

Referring to FIG. 7, the first optical imaging system includes anoptical system including a first lens 210, a second lens 220, a thirdlens 230, a fourth lens 240, a fifth lens 250, an infrared cut-offfilter 260, and an image sensor 270.

In addition, the first optical imaging system includes a reflectionmember P closer to an object than the first lens 210, and having areflection surface that changes a path of light. In the exampleillustrated in FIG. 7, the reflection member P is a prism that changesthe path of the light, in contrast to the example illustrated in FIG. 2,in which the reflection member P is a mirror that changes the path ofthe light.

Respective characteristics (radii of curvature, thicknesses or distances(gaps) between lenses, refractive indices, and Abbe numbers) of lensesare illustrated in FIG. 9.

Since the first optical imaging system moves along an optical axis forauto-focusing, a first position, a second position, and a third positionin the table illustrated in FIG. 10 refer to positions of the firstoptical imaging system depending on a distance from the first opticalimaging system to a subject whose image is being captured. In the tableillustrated in FIG. 10, D0 is the distance between the object and thereflection member P, D1 is the distance between the reflection member Pand the first surface of the first lens 210, and D2 is the distancebetween the second surface of the infrared cut-off filter 260 and theimage sensor 270. As can be seen from the table illustrated in FIG. 10,in this example, the first lens 210 to the fifth lens 250 and theinfrared cut-off filter 260 move along the optical axis forauto-focusing, but the reflection member P does not move along theoptical axis for auto-focusing.

For example, in the table illustrated in FIG. 10, the first position isa position of the first optical imaging system when capturing an imageof a subject at infinity, the second position is a position of the firstoptical imaging system capturing an image of a subject at a normaldistance, for example, about 1.5 m, and the third position is a positionof the first optical imaging system when capturing an image of asubstance at a macro distance, for example, 0.4 m.

A ratio (FOVt1/FOVt3) of a field of view (FOVt1) in the first positionto a field of view (FOVt3) in the third position, that is, a ratio of amaximum field of view to a minimum field of view, is greater than 1 andless than 1.5.

In the example illustrated in FIGS. 7 through 11, the distance TTL fromthe object-side surface of the first lens 210 of the first opticalimaging system to the imaging plane of the image sensor 270 is 9.42 mm,an overall focal length ft of the first optical imaging system is 10.7mm, and an f-number Fno of the first optical imaging system is in arange of 2.6 to 3.1.

In the example illustrated in FIG. 7 through 11, the first lens 210 hasa positive refractive power, and a first surface and a second surfacethereof are convex in the paraxial region.

The second lens 220 has a negative refractive power, a first surfacethereof is convex in the paraxial region, and a second surface thereofis concave in the paraxial region.

The third lens 230 has a negative refractive power, a first surfacethereof is convex in the paraxial region, and a second surface thereofis concave in the paraxial region.

The fourth lens 240 has a positive refractive power, a first surfacethereof is concave in the paraxial region, and a second surface thereofis convex in the paraxial region.

The fifth lens 250 has a negative refractive power, a first surfacethereof is concave in the paraxial region, and a second surface thereofis convex in the paraxial region.

Surfaces of the first to fifth lenses 210 to 250 have asphericalcoefficients as illustrated in FIG. 11. In this example, all object-sidesurfaces and all image-side surfaces of the first to fifth lenses 210 to250 are aspherical.

In the example illustrated in FIG. 7, a stop is disposed in front of thereflection member P, and an effective diameter of at least one of thefirst to fifth lenses 210 to 250 is greater than a diameter of the stop.

In one example, an effective diameter of a lens having a maximumeffective diameter among the first to fifth lenses 210 to 250 is greaterthan the diameter of the stop.

The first optical imaging system configured as described above hasaberration characteristics illustrated in FIG. 8.

According to the examples described above, an optical imaging systemhaving a narrow field of view and being slim, and a portable electronicdevice including the same, may be implemented.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure.

What is claimed is:
 1. An optical imaging system comprising: a pluralityof lenses disposed along an optical axis; and a reflection memberdisposed to be closer to an object than all of the plurality of lensesand having a reflection surface configured to change a path of light;wherein the plurality of lenses are spaced apart from each other bypreset distances along the optical axis; and the condition0.8<TTL/ft<1.1 is satisfied, where TTL is a distance from an object-sidesurface of a lens closest to the object among the plurality of lenses toan imaging plane of an image sensor, and ft is an overall focal lengthof an optical system comprising the plurality of lenses.
 2. The opticalimaging system of claim 1, wherein the plurality of lenses comprise afirst lens, a second lens, a third lens, a fourth lens, and a fifth lenssequentially disposed in numerical order beginning with the first lensfrom an object side of the optical system toward an image side of theoptical system; and the condition 1.5<ft/ft1<3.5 is satisfied, where ft1is a focal length of the first lens.
 3. The optical imaging system ofclaim 2, wherein the first lens has a positive refractive power; and anobject-side surface and an image-side surface of the first lens areconvex.
 4. The optical imaging system of claim 2, wherein the secondlens has a negative refractive power; and an image-side surface of thesecond lens is concave.
 5. The optical imaging system of claim 2,wherein the third lens has a positive refractive power or a negativerefractive power; an object-side surface of the third lens is convex;and an image-side surface of the third lens is concave.
 6. The opticalimaging system of claim 2, wherein the fourth lens has a positiverefractive power; an object-side surface of the fourth lens is concave;and an image-side surface of the fourth lens is convex.
 7. The opticalimaging system of claim 2, wherein the fifth lens has a negativerefractive power; an object-side surface of the fifth lens is concave;and an image-side surface of the fifth lens is convex.
 8. The opticalimaging system of claim 2, wherein object-side surfaces and image-sidesurfaces of the first, second, third, fourth, and fifth lenses areaspherical.
 9. The optical imaging system of claim 2, wherein the first,second, third, fourth, and fifth lenses are plastic lenses.
 10. Theoptical imaging system of claim 2, further comprising a stop disposed infront of the first lens; wherein an effective diameter of a lens havinga maximum effective diameter among the first, second, third, fourth, andfifth lenses is greater than a diameter of the stop.
 11. The opticalimaging system of claim 1, wherein the plurality of lenses comprise: afirst lens having a positive refractive power; a second lens having anegative refractive power; a third lens having a positive refractivepower; a fourth lens having a positive refractive power; and a fifthlens having a negative refractive power; and the first, second, third,fourth, and fifth lenses are sequentially disposed in numerical orderbeginning with the first lens from an object side of the optical systemtoward an image side of the optical system.
 12. The optical imagingsystem of claim 1, wherein the plurality of lenses comprise: a firstlens having a positive refractive power; a second lens having a negativerefractive power; a third lens having a negative refractive power; afourth lens having a positive refractive power; and a fifth lens havinga negative refractive power; and the first, second, third, fourth, andfifth lenses are sequentially disposed in numerical order beginning withthe first lens from an object side of the optical system toward an imageside of the optical system.
 13. A portable electronic device comprising:a first optical imaging system; a second optical imaging system; and athird optical imaging system; wherein the first, second, and thirdoptical imaging systems have different fields of view; and a directionof an optical axis of an optical imaging system having a narrowest fieldof view among the first, second, and third optical imaging systems isdifferent from a direction of optical axes of remaining ones of thefirst, second, and third optical imaging systems.
 14. The portableelectronic device of claim 13, wherein the condition 1.8<FOVw/FOVt<4.5is satisfied, where FOVt is a field of view of the optical imagingsystem having the narrowest field of view among the first, second, andthird optical imaging systems, and FOVw is a field of view of an opticalimaging system having a widest field of view among the first, second,and third optical imaging systems.
 15. The portable electronic device ofclaim 13, wherein the condition 2.0<ft/fw<5.0 is satisfied, where ft isan overall focal length of the optical imaging system having thenarrowest field of view among the first, second, and third opticalimaging systems, and fw is an overall focal length of an optical imagingsystem having a widest field of view among the first, second, and thirdoptical imaging systems.
 16. An optical imaging system comprising: anoptical system comprising a plurality of lenses configured to be movableas a fixed unit along an optical axis to focus on objects at differentdistances while maintaining a fixed positional relationship between theplurality of lenses; and a reflection member configured to reflect lightfrom an object into an object side of the optical system; wherein afield of view of the optical system changes as the optical system movesalong the optical axis; and the condition 0.8<TTL/ft<1.1 is satisfied,where TTL is a distance from an object-side surface of a lens closest tothe object among the plurality of lenses to an imaging plane of an imagesensor, and ft is an overall focal length of the optical system.
 17. Theoptical imaging system of claim 16, wherein the optical systemcomprises: a first lens having a positive refractive power; a secondlens having a negative refractive power; a third lens having a positiverefractive power or a negative refractive power; a fourth lens having apositive refractive power; and a fifth lens having a negative refractivepower; and the first, second, third, fourth, and fifth lenses aresequentially arranged in numerical order beginning with the first lensfrom the object side of the optical system toward an image side of theoptical system.
 18. The optical imaging system of claim 17, wherein thecondition 1.5<ft/ft1<3.5 is satisfied, where ft is an overall focallength of an optical system, and ft1 is a focal length of the firstlens.